Spurs, I've tried a cordovan tab from 3Rivers and think that I get string contact on my lip (not the tab). The tab has fairly thick backing on it.
The best tab that I've shot over the years is a Neet Calf Hair tab, which I trim back a little. This tab is very comfortable, not expensive, but the down side is the hair wears off.
Lately I've been shooting with a Fred Eichler cordovan tab from 3Rivers, and have no lip contact problems with this tab. It was easy to break-in and shows no wear after a lot of shooting. The cordovan and rubber back are thin, so you feel the string, which I like. The best to you.
Jerry